Production of organic phosphorus compounds



Patented Nov. 22, 1949 PRODUCTION OF ORGANIC PHOSPHORUS COMPOUNDS MorrisS. Kharasch, Chicago, 111., assignor to United States Rubber Company,New York, N, Y., a corporation of New Jersey No Drawing. ApplicationJuly 19, 1946,

Serial No. 684,774

3 Claims. 1

This invention relates to a method of producing organic phosphoruscompounds of the type R-P-Halz where R is a halogen-aliphatic radical, Pis phosphorus, and Hal represents halogen.

An object of the invention is to provide a novel method of making theaforesaid chemicals. A further object is to provide a method of makingthe aforesaid chemicals from aliphatic organic compounds having at leastone carbon-to-carbon ethylenic unsaturation. Other objects will beapparent from the following description.

According to the invention, the unsaturated aliphatic compound is heatedwith phosphorus trichloride in the presence of a per-oxy compoundcatalyst or subjected to an agent having similar action, such as actiniclight rays having a wave length below 3000 Angstrom units. The per-oxycompound may be a. diacyl peroxide, such as diacetyl peroxide, ordlbenzoyl peroxide, or other compound having directly linked oxygenatoms. The reaction is preferably carried out in the presence of molalexcess of phosphorus trihalide, generally from 2-20 moles thereof foreach mole of the unsaturated aliphatic compound.

In the case of the compound containing a terminal olefim'c double bond,the reaction may be considered to be as follows:

diacyl peroxide RCH=CH3 PCia RCHCl-CHzPCh heat peroxide (b) R--CH=CHPBr; RCHBr-CH:PBH

or light where R is an aliphatic hydrocarbon radical.

The unsaturated aliphatic compound which is reacted with the phosphorustrihalide, preferably has from 2 to 12 directly linked carbon atoms, forexample, such as ethylene, propene, butene-l, isobutylene, pentene-l,hexene-l, heptene-l, octene-l, nonene-l, decene-l, undecene-i, anddodecene-l.

The primary reaction product may consist of one or more of the compoundsof the type R-P-Hah.

On the basis of the formula RCHCICHzPClz, the compound can be readilydehydrohalogenated to form compounds of the type RCH=CHPCla which inturn can then be hydrogenated to give compounds of the typeRCHzCHz'PClz.

The reaction whereby the constituent atoms of phosphorus trichloride areadded to unsaturated organic compounds to form compounds in which aphosphorus atom is attached to one carbon atom and two halogen atoms areattached to the phosphorus atom and the remaining halogen isattached toanother carbon atom of the organic compound is assumed to proceed via afree-radical chain reaction initiated by the free radicals formed by thedecomposition of the diacyl peroxide. The following outline of thereactions believed to be involved in this new synthesis of organicphosphorus containing compounds is presented in terms of the reactions'involving PCh, a compound of the type RCH=CH2 as a representative of theunsaturated organic compounds operable in the process' and acetylperoxide as representing an acyl peroxide and is intended to beillustrative and not limiting:

ROHCHaPCh PO11 RCHC1CHQYC1L+ -PCI:

R RQHCHzPClz-l-RCH=CH: RCHCHIEE-CHQPCII aonom-cn-omrot P01; -t

R nonolonldn-cmroh moi, concurrently with the above, reactions of thefollowing types are possible:

1) cH,-+ RCH=CH Ron-omen,

( R RoHomon, RoH=cm acn-omtncmcm Reaction (2) may be regarded as thechain initiating step in which the free radical generated by thedecomposition of a primary source of free radicals such as the diacylperoxide interacts with the phosphorus trichloride to form a new freeradical by the removal of a chlorine atom from a P013 molecule. The freeradical formed by this second reaction is then capable of adding to amolecule of the unsaturated organic compound as in (3) to form a thirdtype of free radical which is itself capable as in (4) of reacting witha molecule of P013 to remove a chlorine atom therefrom and to form atthe same time a molecule of the compound RCHCICHzPClz and a free P012radical. The

repetition of steps (3) and (4) constitutes the reaction chain whichleads to the formation of products each molecule of which consists ofthe elements from one molecule of the unsaturated organic compoundtogether with those from one molecule of phosphorus trichloride. Suchcompounds are for convenience referred to hereafter as one-to-onecompounds. Concurrently with reactions (3) and (4) other reactions alsoof a free radical chain type such as those illustrated by (5) and (6)may take place. The formation of products containing in each moleculethe elements from more than one molecule of the unsaturated organiccompound is due to such reaction. and similarly polymeric products maybe formed by reactions such as (7) and (8). When reactions such as (5).(6), 0r (8) p edominate the yield of one-to-one products is undesirablyreduced and I have found that such undesirable side reactions areminimized when the compounds containing the essential group C=CH2 arethose having the type formula R-CH=CH2 in which R, is hydrogen or analiphatic radical.

Example A mixture containing 180 parts (1.6 moles) of octene-l and 1374parts (10 moles) phosphorus trichloride is placed in a two-necked dryflask equipped with a dropping funnel and a reflux condenser. The latteris connected to a tube, the other end of which dips below the surface ofmercury contained in a suitable vessel. The air in the flask isdisplaced by nitrogen and the mixture is heated to 85 C. under asuperatmospheric pressure corresponding to 20 cm. of mercury. 29.6 parts(0.25 mole) of diacetyl peroxide dissolved in 190 parts (1.7 moles) ofoctene-l is added in four equal portions in the course of 2 hours. Whenall the peroxide is added the heating is continued for an additional 2hours. The excess of phosphorus trichloride is removed from the reactionmixture at atmospheric pressure and the excess of octene-l bydistillation at reduced pressure. Fractional distillation at reducedpressure yields 130 parts of a colorless product B. P. 85-88 C./0.5 mm.which has the empirical formula CsH1sCi3P for which the probablestructure is C6H13CHC1CH2PC12.

While certain temperatures and times have been indicated in the aboveexample, it will be and may be widely varied. In general, thetemperature range is from about 25 C. to about 150 C. Further, theamount of'the product obtained will depend on the amount and nature ofthe catalyst employed.

Furthermore, better yields of the desired addition products are obtainedif PBra is used in place of P013.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. Process of producing compounds of the formula RPHalz where R is ahalogen-containing aliphatic radical, P is phosphorus, and Halrepresents halogen, which comprises subjecting a reaction mixturecontaining an olefinic hydrocarbon and a molal excess of a phosphorustrihalide from the class consisting of phosphorus -trichloride andphosphorus tribromide, to the action of a free radical reactioninitiator.

2. Process of producing compounds of the formula RPClz where R is ahalogen-containing aliphatic radical, P is phosphorus, and Clrepresents' chlorine, which comprises subjecting a reaction mixturecontaining an olefinic hydrocarbon and from two to twenty moles ofphosphorus trichloride for every mole of the olefinic hydrocarbon to theaction of actinic light rays of a wavelength below 3000 Angstrom units.

3. Process of producing compounds of the formula RPC12 where R is ahalogen-containing aliphatic radical, P is phosphorus, and Cl representschlorine, which comprises heating a reaction mixture containing anolefinic hydrocarbon, from two to twenty moles of phosphorus trichloridefor every mole of the olefinic compound and a peroxy polymerizationcatalyst to a temperature between 25 C. and 150 C.

MORRIS S. KHARASCH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Morway et a1. Nov. 18, 1941 OTHERREFERENCES Number

